A user interface (UI) denotes an intermediate medium that enables communication between a user and a computer system (a hardware device or a software program).
The UI has advanced a general UI, which recognizes a button type-based input and a touch type-based input, into a natural UI (NUI) that recognizes an input based on a natural gesture of a user.
With the advance of image processing technology for recognizing and tracing an object included in an image, the usability of a natural gesture as an input means is expected to increase, and particularly, in the field of augmented reality (AR) technology, virtual reality (VR) technology, or mixed reality (MR) technology, the usability of a natural gesture as an input means is expected to be very large.
As described above, since the usability of a natural gesture-based input through an NUI is expected to increase, it is required to develop a user authentication system for determining how to perform a user authentication on a natural gesture-based input. However, research and development of a user authentication system for a natural gesture-based input are still insufficient.